Developing quality dairy replacement heifers

Getting calves off to a good start in life will allow the calf the opportunity to grow into a productive cow. Colostrum management is critical for minimizing disease and optimizing growth.
When high quality colostrum is not available or there is a question about the disease status of a cow, 150 to 200 grams of a colostrum replacer can be fed to provide successful passive transfer of immunity.

Management practices for replacement heifers have huge potential to affect farm profitability. For more than 2 decades it has been recommended that replacement heifers should grow at a rate that allows them to calve at 24 months of age or less. However, a recent report indicated average age of US Holsteins at first calving is still substantially higher than this at 26.9 months (Hare et al., 2006). Also, the mortality rate on many farms is higher than desired, which further reducing the supply of replacement heifers.

Much of the success, or failure, of the replacement heifer program is related to care provided during the first two months of life. “Thirty-one percent of all dairy heifer mortality during the first 21 days could be prevented with improved colostrum management” (Dr. Sandra Godden, Univ. of Minn.). Most producers know that providing a clean calving environment and timely feeding of good colostrum is essential for getting calves off to a good start. But, how clean is clean? And what is “good” colostrum?

Calving Environment

The calving area must be clean. Easily monitored facilities allow assistance to be provided when needed as outlined by Drost (2005). Ideally, calving pens provide easy access, are easy to clean, and easily allow for any assistance required to the cow and calf.

After birth when the calf is breathing normally, the naval should be dipped with a 7% tincture of iodine and immediately removed from the dam to minimize exposure to any pathogens present. As outlined in Table 1, a large number of disease organisms are transmitted through fecal contamination and/or direct contact with the dam or other cows in the calving area. Removing the calf from the calving area into a clean environment reduces exposure to these pathogens and reduces the potential for illness. High quality colostrum should be fed as quickly as possible after the calf is removed from the calving area.

Colostrum Feeding and Management

Calves are born without any natural immunity to disease. Colostrum is necessary to provide immunoglobulins (IgG) for protection against diseases. Absorption of IgG in the small intestine is time-dependent and decreases approximately 5% per hour after birth. Essentially no absorption occurs after 24 hours of life. In addition to providing IgG, colostrum binds pathogens to prevent them from colonizing in the small intestine and causing disease.

To achieve successful passive transfer of immunity, it is recommended that calves be fed 2 to 4 quarts of high quality colostrum within 2 hours of birth and another 2 quarts 12 hours later to provide the calf adequate immunity and nutrients to get it off to a good start.

Table 1.

Methods of disease transmission to calves.

Fecal/Oral

Fecal/Naval

Milk

Nasal/Saliva

In Utero

E. coli

E. coli

Johne's

Salmonella

Johne's

Clostridium

Salmonella

BVD

Salmonella

Rota virus

BVD

BVD

Corona virus

BLV

BLV

Coccidia

Cryptosporidia

Johne's

Salmonella

BVD

According to the 2002 National Animal Health Monitoring Survey (USDA, 2002),56.1% of calves were removed from the cow immediately and fed colostrum (Appendix I). The mortality rateof calves left with their dam for 12 to 24-hour was twice that of calves removed from their dam within 4 hours of birth (Jenny et al., 1981). The higher mortality rate is related to increased exposure to disease pathogens and failure of passive transfer of immunity (FPT). Calves left with their dam do not always consume adequate amounts of colostrum and colostrum quality maybe sub-standard. Field data from a calf grower in Florida indicated that approximately 30% of calves with FPT died. Those that did not die required more antibiotic treatments which increased rearing cost. Calves that are sick early in life and recover generally do not grow as well or produce as much milk as calves that were never sick.

Colostrum Quality

Not all colostrum provides adequate amounts of IgG to ensure successful passive transfer of immunity. Colostrum quality is affected by vaccination status, nutrition, stress, age, breed and other factors. A good preventive health program is the first step in stimulating the production of high IgG concentrations in the colostrum. Vaccine choice, timing and route of administration all determine the effectiveness of a vaccination protocol. Diets should be balanced to meet the animal’s nutritional needs using palatable ingredients that are free of mycotoxins. Heat stress should be minimized to maintain intake. Even when all steps are taken to provide each cow with the opportunity to produce high quality colostrum, some do not.

The quality of colostrum should be measured for every batch. Only high quality colostrum from cows tested free of target diseases (in the USA, most commonly; Johne’s, BLV, and BVD) should be fed. Colostrum quality can be measured quickly on farm using a colostrometer. The colostrometer works on the specific gravity of the colostrum, so the higher it floats the better the colostrum quality.

The colostrometer is marked with green, yellow, and red indicators. Green indicates high concentrations of IgG, yellow is intermediate, and red is poor IgG concentration. Colostrum that measures green can be fed without any problems and can be frozen for later use when high quality colostrum is not available.

When colostrum has a lower quality (yellow), a colostrum supplement or replacement should be mixed with the colostrum to provide adequate IgG. Poor quality colostrum (red) should only be fed after the first day of life as it will result in FTP.

The colostrometer readings are sensitive to the colostrum’s temperature. Cooler temperatures overestimate IgG concentrations whereas warmer temperatures underestimate IgG concentrations. Colostrum should be cooled (or warmed when feeding frozen colostrum) to approximately 68 to 74 F before testing. Scientists at Penn State University have developed a spread sheet that allows the reading to be adjusted for temperature if time or conditions do not allow the temperature to be adjusted completely (Table 2).

Table 2.

Corrected Ig values (mg/ml) for colostrum tested with a colostrometer at various temperatures.

Colostrum temperature

4.4 C

18.3 C

32.2 C

40 F

65 F

90 F

Ig as measured (mg/ml)

10

0.4

11.5

22.6

20

10.4

21.5

32.6

30

20.4

31.5

42.6

40

30.4

41.5

52.6

50

40.4

51.5

62.6

60

50.4

61.5

72.6

70

60.4

71.5

82.6

80

70.4

81.5

92.6

90

80.4

91.5

102.6

100

90.4

101.5

112.6

110

100.4

111.5

122.6

120

110.4

121.5

132.6

130

120.4

131.5

142.6

Based on equations from Mechor et al., 1991. Journal of Dairy Science. 74:3940-3943

Pooled Colostrum

Many producers feed pooled colostrum to reduce the risk of FPT, but feeding pooled colostrum can spread diseases such as Johne’s, BLV, or BVD to a large number of calves. For successful control of diseases such as these, pooled colostrum should not be fed.

Another problem associated with feeding pooled colostrum is the potential for bacterial contamination. Strict sanitation protocols for collection and storage, plus rapid cooling are absolutely required to prevent contamination of pooled colostrum. Calves fed contaminated colostrum frequently die within 1 to 3 days after birth. If pooled colostrum is used, a sample should be collected routinely for analysis of bacterial concentrations to monitor sanitation. A strict sanitation protocol must be used for cleaning containers used for handling colostrum (individual or pooled).

Amount of Colostrum Fed

As indicated earlier, most recommend feeding at least 4 quarts of colostrum within 2 hours of birth plus an additional 2 quarts 12 hours later. A recent report suggests long term benefits of feeding 4 quarts of high quality colostrum immediately after birth (Faber et al., 2005). The researchers fed either 2 or 4 quarts of good colostrum immediately after birth plus an additional 2 quarts 12 hours later. Calves were fed whole milk until weaning. The results of the trial are summarized in Table 3. Calves fed 4 quarts of colostrum at birth had fewer health disorders and lower veterinary costs, consistent with previous research. Fewer health disorders and possible positive effects on nutrient absorption resulted in calves with a higher estimated average daily gain (ADG) and earlier age at first breeding. The authors suggested that there was possibly a positive effect on mammary development because 305 d ME lactation records for both first and second lactation were approximately two to three thousand pounds higher than for calves fed only 2 quarts of colostrum at birth.

Additionally, the number of animals culled before completing the second lactation was almost twice as high for the group fed 2 quarts of colostrum compared with that of the group fed 4 quarts of colostrum at birth. These limited data suggest that good colostrum management not only reduces health disorders in calves, but may also improve nutrient digestion and metabolism in the young calf allowing it to grow more efficiently. Additional research supporting these observations suggests that the positive nutrient balance boosts endocrine function related to mammary development. These improvements may also promote changes that support improved milk production and improve the odds of the animal staying in the herd longer

Table 3.

Performance of calves fed either 2 or 4 quarts of colostrum immediately after birth.

Measure

0.53 gallon Colostrum

1.0 gallon Colostrum

Number of calves

37

31

Health disorders

8

5

Medical cost, $/calf

$24.51

$14.77

Estimated ADG, lb/d

1.76

2.27

Age at conception, month

13.97

13.54

305 d ME

First lactation

19,736

21,841

Second lactation

21,257

24,899

Culled, %

24.3

12.9

Source: Faber et al., 2005. Prof. Anim. Sci. 21:420-425.

Colostrum Supplements and Replacements

There are numerous colostrum supplements and replacers on the market. In the US, such products are regulated by the USDA Center for Veterinary Biologics. These products were developed to provide a means of supplying IgG to the newborn calf when high quality colostrum is not available or to provide an alternative to disease control.

Colostrum supplements are produced from bovine colostrum, other milk products or bovine serum and are designed to be mixed with lower quality colostrum to increase IgG intake. Colostrum supplements contain less than 100 grams of IgG per dose and cannot be used effectively to replace good colostrum. These products are intended to be used as a supplement to lower quality colostrum to increase IgG intake and prevent FTP. However, IgG absorption is low for most of these products resulting in higher than desired rates of FTP. Egg-based supplements are poorly absorbed whereas products based on colostrum or whey have variable IgG absorption efficiencies.

Colostrum replacements are produced from bovine serum-based products and provide 100 g or more of IgG per dose. These products also contain fat, protein, vitamins and minerals and can be fed in place of colostrum. Research indicates that the IgG in colostrum replacements is absorbed as effectively as IgG provided by colostrum to support successful passive transfer when fed in adequate amounts (Jones et al., 2003). The success rate of colostrum replacements depends on feeding adequate amounts of the product. The effect of the amount of IgG fed and absorption efficiency is outlined in Table 4.

The amount of IgG that must be fed to provide 100 g of IgG, which is considered the minimum for successful passive transfer, varies with absorption efficiency. These data indicate that at least 150 to 200 g of IgG must be fed to prevent FPT. Producers should check products to see that they will provide adequate amounts of IgG when fed according to directions and that the product is based on bovine serum.

Measuring IgG Status

Failure of passive transfer is generally defined as blood IgG concentrations less than 10 mg/ml at 24 to 48 hours of age. Passive transfer can be evaluated using commercial IgG test kits or measuring blood protein concentrations. Many of the IgG test kits are complicated to run, so most producers use a refractometer to measure blood or serum protein concentrations. Total serum protein concentrations are directly related to IgG concentrations in the blood. The procedure consists of collecting a whole blood sample from a calf anytime between 24 and 48 hours after birth. The sample is allowed to clot or spun in a centrifuge to separate the serum. The serum is collected and placed on a refractometer which directly measures the total protein. Total serum protein concentrations greater than 5.5 mg/dl are considered to indicate successful passive transfer. Concentrations of 5.0 to 5.4 mg/dl indicate moderately successful passive transfer and concentrations less than 5.0 indicate a failure of passive transfer. This simple method can be helpful in trouble shooting health problems related to colostrum management.

Whole Milk or Milk Replacer

Calves can be successfully raised on either whole milk or milk replacers. Whole milk provides more nutrients, but feeding raw whole milk can transmit diseases such as Johne’s or BLV, spread mastitis causing organisms to young calves, and can result in antibiotic residues if a young calf were sold for meat.

If whole milk is fed to replacement heifers, it should be pasteurized. Feeding properly pasteurized milk improves growth rates and reduces the number of days calves have diarrhea or pneumonia. It is essential that pasteurization be done consistently from day- to-day and that the equipment is thoroughly cleaned to prevent bacterial contamination.

Milk that is batch pasteurized should be heated to 145 F for 30 minutes whereas milk that is flash pasteurized should be heated to 162 F for 15 seconds. All employees should be trained on the importance of following operating procedures for pasteurization and sanitation. Producers should keep a daily log that records who pasteurized milk, pasteurization temperatures and times, and cleaning routines.

Traditionally, producers have had good results feeding all-milk milk replacers containing 20% protein and 20% fat. Although milk replacers can be made using plant proteins to reduce cost, calf growth is often unacceptable. More recently, higher protein milk replacers (28% protein and 15 to 20% fat) that are fed at rates of 2.5 lb/d have been used. These products have been shown to increase growth rates and promote greater muscle and frame development, but increase milk replacer and labor cost although cost per pound of gain is equal or lower than traditional programs. These feeding programs are thought to enhance mammary development as well. However, these products may not be as effective when colostrum management is not adequate or if there is increased disease potential. A recent trial with calves that did not have adequate transfer of immunity and were challenged with coronavirus had greater mortality and incidence of scours although they gained more weight throughout the trial (Quigley et al., 2006).

Weaning

Age at weaning varies from farm to farm with a range of 4 to 8 weeks of age. Calves can be successfully weaned from milk or milk replacer when starter intake exceeds 2 lb/d for two consecutive days. The amount of stress the calf is subjected to at weaning increases as diets change, calves change housing environment, and are exposed to other calves and social changes. Intake often drops reducing nutrients needed for growth and immune function. This increases susceptibility to respiratory disease. To minimize stress, newly weaned calves should remain in the same environment for an additional week. When moved to group housing, calves should be grouped by body size and groups kept small (less than 7 head). Adequate feed bunk space should be provided with feed changed gradually. Other activities that increase stress (vaccinations, dehorning, etc.) should be spread out rather than done at weaning. Reducing stress will make the transition for the calf go more smoothly and minimize disease problems.

Summary

Getting calves off to a good start in life will allow the calf the opportunity to grow into a productive cow. Colostrum management is critical for minimizing disease and optimizing growth. At least one gallon of high quality colostrum should be fed within the first 2 hours of life with an additional 2 quarts 12 hours later to provide successful passive immunity. When high quality colostrum is not available or there is a question about the disease status of a cow, 150 to 200 grams of a colostrum replacer can be fed to provide successful passive transfer of immunity. Serum protein concentrations can be measured to determine the success (or failure) of passive transfer of immunity.